"Officially at least — which is to say, on Facebook — Greenpeace International and Facebook are friends. But there are signs they're not getting along. There are those unflattering photos of Facebook that Greenpeace posted, for instance. And that snarky quiz about Facebook's bad habits—that wasn't very nice. And then there's all that stuff Greenpeace has on its own Web site.

What has come between them? And can this relationship be saved? An answer may come as soon as Tuesday, when representatives from the two organizations are scheduled to meet at Facebook headquarters in Palo Alto, Calif. Greenpeace says it's all about Facebook's relationship with coal. But the issue may go deeper than that: Facebook is just way more popular than Greenpeace, and Greenpeace may just be picking a fight to get attention."